Detection Of Leaks In The Cylinders; Detection Of An Accelerometer Fault - SSANGYONG 2004 Rexton 2.7XDi Workshop Manual

DI08-18
This is done periodically under certain operating conditions. When the resetting is finished, the new minimum pulse
value replaces the value obtained during the previous resetting. The first MDP value is provided by the C2I. Each
resetting then allows the closed loop of the MDP to be updated according to the deviation of the injector.

Detection of leaks in the cylinders

The accelerometer is also used to detect any injector which may have stuck open. The detection principle is based on
monitoring the ratio. If there is a leak in the cylinder, the accumulated fuel self-ignites as soon as the temperature and
pressure conditions are favorable (high engine speed, high load and small leak).
This combustion is set off at about 20 degrees before TDC and before main injection.
The ratio therefore increases considerably in the detection window. It is this increase which allows the leaks to be
detected. The threshold beyond which a fault is signaled is a percentage of the maximum possible value of the ratio.
Because of the severity of the recovery process (engine shut-down), the etection must be extremely robust.
An increase in the ratio can be the consequence of various causes:
• Pilot injection too strong
• Main combustion offset
• Fuel leak in the cylinder
If the ratio becomes too high, the strategy initially restricts the pilot injection flow and retards the main injection. If the
ratio remains high despite these interventions, this shows that a real leak is present, a fault is signaled and the engine
is shut down.

Detection of an accelerometer fault

This strategy permits the detection of a fault in the sensor or in the wiring loom connecting the sensor to the ECU. It is
based on detection of the combustion. When the engine is idling, the detection window is set too low for the combustion
caused by the main injection. If the ratio increases, this shows that the accelerometer is working properly, but otherwise
a fault is signaled to indicate a sensor failure. The recovery modes associated with this fault consist of inhibition of the
pilot injection and discharge through the injectors.
CHANGED BY
EFFECTIVE DATE
AFFECTED VIN
ENGINE CONTROL SYSTEM
DI ENG SM - 2004.4